Effect of preoperative oral erythromycin, erythromycin-ranitidine, and ranitidine-metoclopramide on gastric fluid pH and volume.

Study Objective: To determine whether combining erythromycin with ranitidine is more efficacious than erythromycin or established ranitidine-metoclopramide combination in reducing the volume and acidity of gastric aspirate.

Design: Randomized, double-blind study.

Setting: Operating room complex.

Patients: Eighty ASA physical status I and II patients.

Intervention: Patients were divided into 4 groups of 20 patients each. All patients received the study medication (in tablet form) packed in identical gelatin capsules 60 to 90 minutes before surgery in the premedication room. Patients in group PP were given two placebo tablets; group EP received erythromycin 250 mg, and placebo; group ER received erythromycin 250 mg, and ranitidine 150 mg; and group RM was given ranitidine 150 mg, and metoclopramide 10 mg.

Measurements: After tracheal intubation, gastric fluid was aspirated via orogastric tube, and volume and pH of the aspirate were studied.

Results: Significantly higher gastric volume occurred in group PP than groups EP, ER, or RM (P < 0.001). There were no differences in volumes among groups EP, ER, and RM. Gastric pH was significantly lower (P < 0.001) in groups PP and EP than in groups ER and RM.

Conclusion: Erythromycin and ranitidine combination is more efficacious than erythromycin alone in reducing the acidity and volume of gastric fluid. No difference was found between erythromycin-ranitidine and ranitidine-metoclopramide combination.